Steam-boiler.



A. D. PRATT.

STEAM B0|LR.

APPLICATION FILED ma. 8. 1911.

1 ,267, 1 14:. Patented May 21, 1918.

4 SHEETS-SHEET I.

INVENTOR. M14- a- B I /A-A TTORNEYS.

A. D. PRATT.

STEAM BOILER.

APPLICATION FILED FEB. 8. I917.

Patented May 21,1918.

4 SHEETS-SHEET 2.

NVENTOR. Maw

/ A TTORNEYS.

A D. PRATT.

STEAM BOILER.

APPLICATION mm FEB. 8. I917.

Patented May 21, 1918.

4 SHEET$SHEET 3- INVENTOR.

in 81/ 2 'a z ATTORNEYS.

A. D. PHAT].

STEAM BOILER.

APPLICATION mm ran. a. 19:24

1,267, 1 14. Patented May 21,1918.

4 SHEETS-SHEET 4.

IZZZZZ ZZMW I M W INVENTOR. BY J A M ATTORNEYS.

UNITED STATES PATENT OFFICE.

ARTHUR D. PRATT, OF NEW YORK, N. Y., ASSIGNOB TO THE BABCOCK & WIBOOI COM- PANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

STEAM-BOILER.

Specification of Letters Patent.

Patented May 21, 1918.

To all whom it may concern:

Be it known that I, ARTHUR D. PRATT, a citizen of the United States, residing at New York city, borough of Manhattan, county of New York, and State of New York, have invented certain new and useful Improvements in Steam-Boilers, of which the following is a specification.

My invention relates to steam boilers and more particularly to those of the general Stirling type and will be understood by reference to the accompanying drawings in which Figure 1 is a vertical lon 'tudinal section of one embodiment thereo certain parts being broken away. Figs. 2, 3 and 4 are similar views showing modifications as will be described more fully hereinafter. Similar reference numerals indicate similar parts in the several views.

Referring to Fig. 1, the boiler shown comprises transverse upper steam and water drums 1, 2 and 3 and a mud drum 4, the upper drums being connected to the mud drum by banks of tubes 5, 6 and 7. I may use a single mud drum 4, as shown, or a series of connected mud drums, and I intend to cover both structures by the words lower chamber in the claims. The three upper steam and water drums must, however, be connected to this lower chamber whether in the form of one drum or several connected drums. The steam space of the center drum 2 is interconnected with the front and rear drums by curved steam circulatin tubes-8 and 9. The water spaces of the ront and middle drums are connected by water circulating tubes 10, the upper row of which tubes support tiling 11. In the forms shown there are no water circulators between the middle and rear steam and water drums. A baflle 12 is supported upon the first row of tubes of the front bank and extends upwardly from a point back of the bridge wall 13 to the upper end of the bank. A suitable seal 14 extending from tube clam s at the lower ends of the front row of tu es of the bank 5 to the bridge wall 13 prevents short circuiting of the gases, as more lparticularly descr bed in the application of S. J acobus, Serial No. 55,771, filed October 14, 1915.

The middle bank of tubes 6 is provlded with two baflies, one of which 15 is supported upon the first row of tubes and extends downwardly from the middle steam and water drum, and the other, 16, is supported upon the rear row of tubes and extends u wardly from the mud drum. A cross ba 0 or shelf 17 extends from the baflie 16 to substantially the first row of tubes of the rear bank. In the latterbank is a baffle 18 supported upon tubes at the rear of the bank and extending downwardly from the rear steam and water drum. The gases flow upwardly in front of the front bank of tubes, across the latter bank at the upper part thereof into the secondary combustion chamber 19, downwardly over the tubes of the front bank at the rear of bafile 12, thence upwardly over the tubes of the middle bank, downwardly over the tubes of the rear bank and then upwardly in the final pass back of the rear bank to the outlet 20.

As shown in Fig. 1, the furnace gases pass over a comparatively small portion of the heating surface before enterin the chamber 19 permitting thereby an e ective secondary combustion in this chamber. If desired, a superheater may: be placed in the chamber 19. In the form shown such superheater comprises the cross boxes 21 and 22 to which the upwardly projecting U-tubes 23 are connected. The boxes are supported in saddles resting upon the cross beam 24 forming art of the structural work of the setting. he outlet box 22 is at a higher level than the inlet box 21 and is placed in roximity to the rear row of tubes of the rent bank but far enough away therefrom to allow for the easy expansion of the superheater tubes into the box 22, and to allow a boiler tube to be passed between the rear of the front bank of tubes and said box when replacing a boiler tube. The outlet box 21 is in close proximity to the middle bank of tubes, such spacing apart of the superheater boxes lessening the overturning moment of the superheater tubes and providing a superheater which does not require supports for the tubes other than the cross boxes or headers.

In the standard Stirling boiler the front and rear steam and water drums are on substantially the same level and below the middle drum, and the main steam outlet is placed on top of the middle drum Accordmg to the arrangement shown in Fig. 1 the rear steam and water drum is set hi her than the usual practice, and on substantially the same level as the middle drum, and the main steam outlet 25 is placed on top of the rear drum.

In the steam space of the rear drum is a dry pipe 26, the main steam outlet connecting therewith and delivering the steam to the inlet box 21 of the superheater. A feed pipe 27 enters the top of the rear drum 3 and discharges into a trough from which the water is distributed to the drum. A plate 28 is placed in the rear drum between the steam inlets 9 and the dry pipe 26 to deflect any water in the steam toward the bottom of the drum. With the steam spaces interconnected as shown, the water level in the rear drum will at all times be well below the level of the dry pipe. Experiments have demonstrated that the water level in the rear drum of a standard Stirling boiler with the steam space of the middle drum interconnected to both the front and rear drums by steam circulating tubes, is higher under certain conditions of operation with water containing a material amount of elements in solution than it is with a purer water. It is, therefore, not only advantageous, but highly important, to raise the rear drum to the level of the middle drum when the feed water is of such nature that it will lead to relatively high concentrations in the water contained in the boiler.

The form shown in Fig. 1 is especially adapted to waters containing im urlties which tend to produce foaming an primin and drier steam can be secured and supplied to a superheater than with a standard arrangement in which the steam is taken from the middle drum. By raising the rear drum above the standard position, the dry pipe 26 is correspondingly raised above the water level in the rear drum and this eliminates any trouble which mi ht occur when there is high water in the oiler, with the rear drum at a lower level because of water being carried along with the steam into the dry pipe. Even should there be a high deee of concentration of foreign elements 1n the water in the boiler, tending to produce riming, the steam supplied to the supereater will be comparatively dry and by reason of this a superheater of a given size will give a greater degree of superheat under such conditions, t an in the standard construction in which the steam is taken from the middle drum.

The drums are of the usual type that is, made up of a shell sheet and a tu e sheet, butt-'ointed and secured with double longitu inal straps 29. In order to deflect the gases downward after they leave the u per part of the middle bank of tubes an to prevent direct impingement of the gases upon the rear steam and water drum, and to protect the butt stra s of the middle and rear drums, I provi e a special baflie 30 which extends from the middle drum below the rear butt strap thereon, to a point below the rear steam and water drum, substantially as shown. This bafile is shown as inclined downwardly from the middle steam and water drum and is supported upon the bent upper ends of a row of tubes 31 extending from the lower water chamber and passing in close proximity to the rear upper drum, and with their upper ends connected to the middle upper drum. Not onl' are the middle and rear drums protecte in the manner stated but the special bafile 30 prevents the hot gases striking the upper portions of the tubes of the rear ban When the boiler is run at high ratings the water level may fall below the top of the tubes, and by preventing the hot gas from striking the tops of the tubes the danger of overheatin the tubes is eliminated.

In ig. 2 I have shown my special protecting baffle 30 in a Stirling boiler having the standard bafliing, but with the rear steam and water drum on substantially the same level as the middle steam and water drum, as in Fig. 1, and another type of superheater in the chamber between the front and middle banks. In this form a bafile 32 is supported upon the rear row of tubes of the front bank 5 and extends upwardly from the mud drum to the upper part of the bank. A baflie 33 is supported u on the rear row of tubes of the middle ba 6 and extends downwardly from the middle steam and water drum 2. Horizontal shelves 34 extend from the rear wall of the setting toward the rear bank. The gases flow upwardly along and among the tubes of the front bank, thence in a general downward direction over and among the tubes of the middle bank, thence upward over the tubes of the rear bank to the outlet 20. If desired, a superheater may be placed in the chamber between the front and middle banks of tubes. In the form shown in Fig. 2, the superheater comprises cross boxes 35 and 36 to which the 'upwardl projecting U- tubes 37 are connected. T e tubes, in this form of superheater, extend substantially parallel with the tubes ofthe middle bank, their u per ends bein in close proximity to the mi dle steam an water drum. Clamps secured to the front row of boiler tubes of the middle bank serve as supports for resisting the overturning moment of the superheater. The main steam outlet 25 is placed upon the rear steam and water drum and the steam is conducted therethrou h to the superheater inlet box 36. An oi burning furnace is shown, the atomizers 39 being set in recesses in the bridge wall 40.

In Fig. 3 is shown a boiler having a baffle arran ement for the banks of tubes as in Fig, but with the rear steam and water drum 3 set upon substantially the same level as the front steam and water drum 1, and the main steam outlet 38 set upon the top of the middle steam and water drum as in standard practice. The dry pipe 26 is, of course, transferred from the rear steam and water drum to the middle steam and water drum. Otherwise the parts are the same as in Fig. 1,

Fig. 4 shows a Stirlin boiler standard both as to the baflling for e banks of tubes, the setting of the steam and water drums and the location of the main steam outlet. Except for the difierence in location of the rear steam and water drum 3, and the location of the main steam outlet 38, the parts 2nd their arrangement are the same as in What I claim and desire to secure by Let ters Patent of the United States is:--

1. A steam boiler of the class described comprising at least three upper transverse drums connected by banks of tubes to a lower water chamber, baflles for the gases over and me the tubes of sai banks, some of the tubes of-the rear bank being connected to the middle upper drum, and a baflie supported upon the upper portions of said last-named tubes to rotect the rear uppe'r drum from excessive flea 2. A steam boiler of the class demnbed comprising at least three upper transverse drums connected by banks of tubes to a lower water chamber, baflles for direc the gases over and among the tubes of sai banks, the front row of tubes of the rear bank being connected to the middle upper drum, and a bafile supported u n the upper portions of said last-named t to protect the rear upper drum from excessive hea 3. A steamt lioiler of the class descri comprising a cast three upper dmmsconnectedbybanksoftubestoa lower water chamber, for directing erg the gases over and among the tubes of said banks with an up-pass in the middle bank, some of the tubes of the rear bank being connected to the middle upper drum, and a ballie supported upon the upper portions of said last-named tubes to protect the rear upper drum from excessive heating.

4. A steam boiler of the class described comprising at least three upper transverse drums connected by banks of tubes to a lower water chamber, the rear upper being at a higher level than the front u per drum, a mam steam oiftake leading rphm' said rear drum, baflies for directin over and amon the tubes 0 said anks, some of the tu of the rear bank being connected to the middle upper drum, and a Special baflle supported u on the upper en of said last-named tu for protecting the middle and rear upper drums from excessive heating.

5. A steam boiler of the class described comprising at least three upper transverse drums connected by banks of tubes a lower water chamber, bafiles for d1 the gases over and among the tubes of sea banks, steam circulators connecting the 13)- r drums, water circulators between a ifont and middle u per drums, a feed water inlet leading into 0 rear upper drum, the front row of tubes of the rear bank being connected to the middle upper drum, and a bame supported upon the upper portions of said last-named tubes to protect the-rear rdrumfromexcessivehea' testimony whereof I have unto signed my name in the presence of two subscribing witn ARTHUR D. PRATT.

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